Molded plastic sanitaryware and plastic industrial vessels have experienced steadily increasing sales in the last few decades. Both thermoplastic and thermosetting resins have been employed in the materials used for these products. U.S. Pat. No. 4,267,229, for example, discloses decorative acrylic sheets and formed articles for this purpose. The sheets are of the cast solution methacrylate type formed by polymerizing a monomer mixture in a closed cell. The colored acrylic sheet is formed from polymer in monomer syrup containing a mixture of pigments and the invention pertains specifically to the concentration of pigments towards one surface.
Structurally reinforced composites comprising a thermoplastic vessel such as polymethylmethacrylate and a rigid foam backing of blown polyurethane are disclosed in U.S. Pat. No. 4,784,904. Recycling of the rigid polyurethane foam is not economical.
National standards have been implemented by the plumbing industry through ANSI regulations such as Z124.1 for plastic bath tub units and Z124.2 for shower stalls. Type 4 tubs are defined as units having a thermoplastic sheet material which is formed over a mold and containing a structural base. The sheet material must conform to a variety of performance standards such as impact strength, load strengths at various locations on the article, ignition tests, and others. The present invention pertains to the structural base component.
Increased attention is becoming focused on the flame and smoke characteristics of plastic sanitaryware as permanent installations in commercial or residential buildings. Future efforts to conform these articles to building codes covering permanent installations gives rise to a technical challenge in designing cost effective plastic replacements for conventional porcelain, steel or thermosetting resin-based sanitarywares and which will exhibit reduced flammability and smoke emission.
Rigidity standards under ANSI require a specified performance level for the floor and sidewalls of plastic sanitaryware. There is a maximum allowable deflection under a specified load for the floor and sidewalls. A trend in commercially available polymer-based sanitaryware articles has been to reduce the weight of material comprising the show surface layer, which leads to thinner wall thickness and reduced flexural strength.
Exemplary show surface layers are made from polymethylmethacrylate, polystyrene, gel coat, and thermoset castings from sheet molding or bulk molding compounds. Show surfaces are structurally reinforced by spray-up or lay-up FRP fiber reinforcements underneath. Exemplary thermoset resin in the FRP layer includes glass reinforced unsaturated polyester which present limitations for recycling.
The forming method for spray-up/lay-up is essentially manual, and requires a post-lay-up curing period, during which time volatile organic compounds (VOC) are emitted. With current legislative mandates focusing on the elimination of volatile organic components, this will place greater importance for non-VOC emitting structural components.
It would be desirable from an economic standpoint to enable a reduction in the wall thickness of a thermoformed vessel, substantially eliminating VOC emission, and providing easy recycling without sacrificing rigidity in the structure. The present invention provides such structural support and furthermore is adaptable for reduced flammability and smoke emission for residential and commercial sanitaryware installation. Reusable structural support articles for plastic industrial vessels would also be attractive as replacements for pallets and other supports not as durable for re-use.